Electrical power is distributed from central generating plants to homes, offices, and factories as three-phase alternating current. In recent years there has been an increasing public concern about possible biological effects of the low frequency electric and magnetic fields associated with the distribution and use of electrical power. Apparatus and methods for reducing such fields have been addressed by the inventor in his U.S. Pat. Nos. 5,070,441, 5,147,983, and 5,175,442, the disclosures of which are herein incorporated by reference.
Although much of the recent public outcry has been directed at high voltage transmission lines on designated rights of way, there is also a perception that substations, especially those near schools, may be a public health hazard. Measurements of electrical or magnetic fields near substations show that these fields are almost entirely caused by the power lines that enter and exit the substation. It is known that the use of coaxial cable with the outer conductor connected to an earth ground eliminates the electric field. It is also well known that there are parasitic losses associated with the use of coaxial cable and that in some cases the magnetic field measured on the surface of the earth may actually be higher over burled coaxial cables than immediately under an overhead power line.